Power semiconductor modules usually comprise a power electronics substrate, on which a plurality of power semiconductor components (for example semiconductor switches such as IGBTs (insulated-gate bipolar transistors) or MOSFETs (metal oxide-semiconductor field-effect transistors) are arranged. The power electronics substrate can be fixed (e.g., adhesively bonded) directly in a housing part (a so-called module frame). Alternatively, the power electronics substrate can also be fixed (e.g., soldered) on a metallic baseplate, which is in turn arranged on a module frame. In this case, the baseplate practically forms the housing base of the power semiconductor module. The module frame is usually produced from plastic and in the injection-molding method, for example.
The power electronics substrate can be in particular a DCB substrate (DCB=double copper bonded), a DAB substrate (DAB=double aluminum bonded) or an AMB substrate (AMB=active metal braze), in which the insulation carrier usually consists of ceramic. A further power electronics substrate is the so-called IMS substrate (IMS=insulated metal substrate), in which a metallic carrier is insulated from the metallization by a thin insulation layer. A metallization is arranged on both sides of the carrier (insulated metal or ceramic). The metallization on the top side is structured and therefore has conductor tracks, soldering pads and bonding pads and the like. The metallization on the underside is usually over the whole area.
The power semiconductor components arranged on the substrate are generally soldered by their rear side (underside) onto the metallization at the top side. The power semiconductor components are usually contacted with metallic terminal areas (bonding pads) on the insulating substrate by means of bonding wires. Terminal lines, e.g., contact pins, form external terminals which are led through the housing and enable the terminal areas to be contacted externally.
Semiconductor modules and in particular power semiconductor modules generate heat during operation at high currents and voltages, which heat, if it is not correspondingly dissipated, reduces the power and lifetime of the modules. In the case of power semiconductor components and modules, in the case of correspondingly high power losses, liquid cooling is usually used in order to ensure sufficient heat dissipation.
In the case of direct liquid cooling, the power semiconductor module has heat exchangers (e.g., heat sinks) at its underside, which absorb the heat from the components and transfer the heat to the cooling liquid by virtue of the direct contact therewith. Consequently, the cooling liquid is heated while it flows along the underside of the module, the temperature of the cooling liquid getting ever closer to the operating temperature of the module. Often a multiplicity of power semiconductor modules are arranged one behind another along a single heat sink. In this case, the heat sink can be for example an elongated straight heat sink or a U-shaped heat sink. Arrangements are also known in which a further heat sink is arranged on the top side of the power semiconductor modules in order to double the area for dissipating heat.
In many applications it is desirable to measure the current flowing through at least one of the external terminals. However, the space for a current measuring arrangement is limited on account of the close arrangement of the power semiconductor modules along the heat sink or heat sinks. In addition, electrical isolation of the power semiconductor module and the evaluation electronics is required. In known arrangements, therefore, current measuring arrangements are connected to the corresponding terminals of the power semiconductor module externally by means of a busbar. The current supply of the current measuring arrangements and the data transfer to a control and/or evaluation module are implemented here by means of corresponding supply and data lines. However, a large amount of additional space is required for the current measurement in the case of such arrangements as a result of the additional current measuring arrangements.